1. Technical Field
The present invention relates to an optical image capturing module, and in particular, to an optical image capturing module formed by four prisms, a first wavelength-selective-coating film, a second wavelength-selective coating film, and a beam splitting coating film group, and a method of aligning upper and lower substrates and a method of observing upper and lower substrates, which use an optical image capturing module of the present invention.
2. Related Art
U.S. Pat. No. 3,684,384 provides a composite optical prism module, which is formed with a truncated quadrangular, right prism with a 45° truncation and a rectangular prism united to the optical prism module to form a parallelepiped with a half-silvered mirror film at their interface and with a total reflecting mirror film at the vertical surface of the rectangular prism, so that the two components which are opposed in their mated positions can be superposed in the same coordinate space for image observation. However, in the disclosure of the prior art patent, two different right-angled prisms are used, so the path lengths of upper and lower ray paths are different, a manner of setting up a light source is limited, and the volume of the composite optical prism module is large.
U.S. Pat. No. 5,519,535 also discloses a composite optical prism, which is formed with two right-angled prisms to achieve the same optical effect with U.S. Pat. No. 3,684,384. In addition, a liquid crystal optical shutter is added to separately control presentation of images of objects at different sides. However, in the disclosure of the prior art patent, the liquid crystal optical shutter sacrifices the efficiency of the light intensity to some extent, and there are many control elements.
U.S. Pat. No. 4,574,197 discloses a dual field of view sensing device, in which a polygonal prism is mainly used to refract a ray through mechanical turning control, and then two parallel ray paths are reflected to the same sensor at the same time, so that a symmetrical ray path is achieved. Switching of ray paths is determined by turning locations of the polygonal prism, that is, two different ray path sources are reflected to the same plane space through a prism. However, the volume of the apparatus disclosed in the prior art patent is excessively large, a designed ray path is excessively long, and mechanical control is excessively complicated.
In the prior art, if two ray paths from different sources are mapped into the same plane space at the same time, main attention is focused on ray path design of a prism, which is mostly common in the foregoing prior art patents (U.S. Pat. No. 3,684,384 and U.S. Pat. No. 5,519,535). A composite right-angled prism reflects ray paths of an upper to-be-detected object and a lower to-be-detected object to the same image plane, which may cause the problem of inequality of path lengths of the opposite light rays from the upper to-be-detected object and the lower to-be-detected object. If image capturing is considered, the inequality of optical working distances may be caused, leading to that the upper to-be-detected object and the lower to-be-detected object is placed at asymmetrical distances, which may cause a complicated manufacturing process after alignment. Moreover, refraction paths are many in number, and sizes are too large for all current composite prism modules, so the composite prism modules do not conform to a process of the current optoelectronic industry.
Therefore, there is a need to provide an optical image capturing module having a symmetrical ray path, which can solve the foregoing problems.